On Tuesday, July 21, 2015 at 8:06:49 AM UTC-6, lisarden wrote: By the way I with my collegues spent some time on investigating this issue > and found in the tps65217 datasheet that all three power source Vac, Vusb > and Vbat should not be enabled at the same time. Only two of them should. > Because of the reason that BBB is a universal enthusiast's board all three > power sources are left floating, which contradicts with tps65217 > architecture. We figured out that if the most of users use only a barrel > connector or USB then Vbat input should be grounded. I don't know if this > solution fixes the random reboot issue but at least it complies with the > TPS65217 architecture. Probably anybody should try to ground the Vbat input > and see how the board behaves. >
I was reviewing the TPS65217 datasheet and I think this may be the area of concern (from section 9.3.9.1): The linear charger periodically applies a 10-mA current source to the BAT > pin to check for the presence of a battery. This will cause the BAT > terminal to float up to > 3 V which may interfere with AC removal detection > and the ability to switch from AC to USB input. For this reason, it is not > recommended to use both AC and USB inputs when the battery is absent. Since the battery is absent for most BBB users, TI recommends using AC or USB power, but not both. Furthermore, the TPS65217 has internal sinks on the AC and USB inputs, so it should not be necessary to short either input to ground when it is not used as long as the input sinks have not been forced off by the software. 9.3.9.4 AC and USB Input Discharge > > AC and USB inputs have 90-µA internal current sinks which are used to > discharge the input pins to avoid false detection of an input source. The > AC sink is enabled when USB is a valid supply and VAC is below the > detection threshold. Likewise, the USB sink is enabled when AC is a valid > supply and VUSB is below the detection limit. Both current sinks can be > forced OFF by setting the [ACSINK, USBSINK] bits to 11b. Both bits are > located in register 0x01 (PPATH). > > NOTE [ACSINK, USBSINK] = 01b and 10b combinations are not recommended as > these may lead to unexpected enabling and disabling of the current sinks. 9 > Perhaps someone can check if these are being set to something other than 00b. Dennis Cote -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
